Substituted styrenes are known compounds which are used in the production of photoresists, adhesives, coating compositions, pharmaceuticals, ultraviolet-absorbing sunscreen agents and other like compounds. More particularly, they are used as intermediate monomers for the production of polymers used for the preparation of said compounds.
A well known substituted styrene compound is 4-acetoxystyrene. The monomer 4-acetoxystyrene is a stable monomer which can be readily polymerized and copolymerized to low, medium and high molecular weight polymers. The monomer readily polymerizes in solution, suspension, emulsion or bulk using well-known free radical catalysts such as, for example, the peroxide and azo compounds. Such polymerization can take place in the absence of comonomers whereby the resultant product is a homopolymer or in the presence of comonomers whereby the resultant product is a copolymer. Examples of processes used for the production of homopolymers or copolymers of 4-acetoxystyrene are the processes disclosed in U.S. Pat. Nos. 4,822,862, 4,912,173 and 4,962,147. Other well-known processes can also be used.
In the case of copolymerization, the most commonly used comonomer is styrene. Other comonomers include vinyltoluene; alpha-methylstyrene; ortho-, meta-, and para- cloro- and bromostyrene; the diene monomers such as butadiene; the acrylate and methacrylate ester monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, butyl methacrylate and 2-ethylhexyl acrylate; acrylonitrile; methacrylonitrile; the polymerizable acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and the like; and the allyl ester comonomers described in U.S. Pat. No. 4,877,843. The homopolymers and the copolymers of 4-acetoxystyrene can be hydrolyzed to produce homopolymers and copolymers of 4-hydroxystyrene which are well-known compositions used in the manufacturing of metal treatment compositions, photoresists, epoxy resins and epoxy resin curing agents. Processes for the conversion of homopolymers and copolymers of 4-acetoxystyrene to homopolymers and copolymers of 4-hydroxystyrene are disclosed in U.S. Pat. Nos. 4,678,843, 4,689,371, 4,822,862, 4,857,601, 4,877,843, 4,898,916, 4,912,173, and 4,962,147.
Several methods have been developed for the production of the monomer 4-acetoxystyrene. Corson, et al., Preparation of Vinylphenols and Isopropenylphenols, 23 J. Org. Chem. 544-549 (1958), discloses a process for making 4-acetoxystyrene from phenol. According to the process, phenol is acylated to 4-hydroxyacetophenone which is then acetylated to 4-acetoxyacetophenone. The latter compound is hydrogenated to 4-acetoxyphenylmethylcarbinol, which is, then, dehydrated to 4-acetoxystyrene. Another process for the preparation of 4-acetoxystyrene is disclosed in copending U.S. patent application Ser. No. 07/548,170, now U.S. Pat. No. 5,041,614, which is incorporated herein and is made part hereof by reference. In that process, 4-acetoxyphenylmethylcarbinol is dehyrated in the presence of acetic anhydride and an acid catalyst to form 4-acetoxystyrene. The compound 4-acetoxyphenylmethylcarbinol is sometimes referred to herein for brevity and convenience as "APMC."
Copending U.S. patent application Ser. No. 07/598,510, now U.S. Pat. No. 5,151,546, discloses methods of preparing APMC. One method involves heating 4-acetoxyacetophenone at a temperature of from about 54.degree. C. to about 120.degree. C. and at a pressure of about 14.7 psig to about 5000 psig in the presence of at least a stoichiometric amount of hydrogen and a catalyst selected from the group consisting of Pd/C or activated nickel in the absence of a solvent. Another method involves the hydrogenation of 4-acetoxyacetophenone with a suitable reagent such as NaBH.sub.4, lithium aluminum hydride, hydrogen and diisobutyl aluminum hydride in the presence of a solvent.
Another method of preparing 4-acetoxystyrene is disclosed in copending U.S. patent application Ser. No. 07/598,510 which is incorporated herein and is made part hereof by reference. APMC is dehydrated in the presence of a dehydrating agent such as KHSO.sub.4, alumina, titania, silica gel and mineral acids. The reaction is carried out under substmospheric conditions at a temperature in the range of 85.degree. C. to 300.degree. C. for about 0.2 to about 10 minutes.
Examples of other substituted styrene derivatives are disclosed in U.S. Pat. Nos. 4,868,256; 4,868,257; 4,933,495; 4,927,956 and 4,965,400. U.S. Pat. Nos. 4,868,256; 4,868,257 and 4,933,495 disclose methods for producing substituted styrenes and, more particularly, 3-mono or 3,5-disubstituted acetoxystyrene by dehydrating 1-(3'-mono or 3',5'-disubstituted-4'-acetoxyphenyl) ethanol with an acid or a base and hydrolyzing said product to produce 3-mono or 3,5-disubstituted hydroxystyrene. The substituents are selected from the group consisting of Cl, Br, I, NO.sub.2, NH.sub.2, SO.sub.3 H or C.sub.1 -C.sub.10 alkyl. Furthermore, those patents disclose a method of producing 3-bromo-4-acetoxy-5-methylstyrene from 1-(3'-bromo-4'-acetoxy-5'-methylphenyl)ethanol.
U.S. Pat. No. 4,927,956 discloses 3,5-disubstituted-4-acetoxystyrene wherein the substitution is independently C.sub.1 to C.sub.10 alkyl or alkoxy or amino; and substituted 4-hydroxy- and 4-acetoxystyrene compounds wherein the substitutes in the 2,3 and 6-positions are independently hydrogen, alkyl, alkoxy or halogen and the substitute in the 5-position is chlorine or bromine.
U.S. Pat. No. 4,965,400 is directed to a method of preparing 3,5-disubstituted-4-acetoxystyrene by dehydrating 1-(3',5'-disubstituted-4'-acetoxyphenyl)ethanol wherein each of the 3,5-substitutions are independently C.sub.1 to C.sub.10 alkyl or alkoxy, amino or halogen. The reaction is carried out in the presence of an acid dehydrating agent.
Although several methods were employed in the past for the preparation of substituted styrenes, none of those methods involved the preparation of such substituted styrenes from bisarylalkyl ethers such as 4,4'-(oxydiethylidene)bisphenol diacetate or 4,4'-(oxydiethylidene)bisphenol dimethyl ether.
4,4'-(oxydiethylidene)bisphenol diacetate which is otherwise identified as bis (4-acetoxyphenylmethylcarbinol) ether is sometimes referred to herein for brevity and convenience as "APMC-Ether." The compound 4,4'-(oxydiethylidene)bisphenol dimethyl ether which is otherwise identified as (4-methoxyphenylmethylcarbinol) ether is sometimes referred to herein for brevity and convenience as "MPMC-Ether."
APMC-Ether is a compound isolated from a species of mushrooms as disclosed in F. Bohlmann et al., Phytochemistry 18(8), 1403 (1979). Furthermore, APMC-Ether is formed as an impurity in the acid catalyzed dehydration of APMC to 4-acetoxystyrene monomer and in the thermal treatment of APMC during its purification.
In the past, there were no uses for APMC-Ether. Accordingly, APMC-Ether removed from mixtures containing it as an impurity required disposal in landfills or similar disposal sites thereby giving rise to economic and environmental burdens. According to the present invention, APMC-Ether is used to produce 4-acetoxystyrene whereby the aforesaid economic and environmental burdens are eliminated.
In addition to disclosing a method of preparing substituted styrene derivatives from bisarylalkyl ethers, the present invention discloses a method of preparing such bisarylalkyl ethers from corresponding arylalkanols. Such method is preferably used for the preparation of APMC-Ether from APMC and for the preparation of MPMC-Ether from 4-methoxyphenylcarbinol which is sometimes referred to herein for brevity and convenience as "MPMC." No such method was disclosed by the prior art.
These and other advantages of the present invention will become apparent from the following description.